1. Field of the Invention
The present invention relates generally to a system for removing water, such as rain drops, from a surface. More specifically, the invention relates to a system for shaking water off an automotive or ship windshield surface, a mirror surface, lens surface and so forth.
2. Field of the Invention
The Japanese Utility Model First Publication (Jikkai) Showa No. 60-106862JJ discloses a system for shaking water off a windshield. In the disclosed system, a electromagnetically operable driver is provided for transmitting vibration or oscillation energy for the windshield. Oscillation of the windshield is transmitted to water, such as rain drops, on the windshield. The oscillating energy thus accumulated in the water and becomes greater than surface tension of the water. This causes the water to be shaken off the windshield.
In order to efficiently transmit the oscillating energy generated by the driver, it is preferable to set the frequency of oscillation in a range substantially corresponding to the resonating frequency range of the windshield.
A difficulty is encountered in setting the oscillation frequency to be generated by the driver. Namely, the resonating frequency of the windshield tends to vary depending upon variation of its mass. The mass varies depending upon the amount of the water on the windshield. That is to say that as the amount water on the windshield decreases so does the total mass of the windshield. This tends to cause the set oscillation frequency of the driver to be different than the resonating frequency of the windshield. When the frequency of the oscillation transmitted from the driver becomes different from the resonating frequency of the windshield, efficiency with which the windshield is oscillate by means of the driver become significantly driven is lowered. This results in significant drop of efficiency in removal of the water from the windshield.